Voltage conversion systems are used in situations where a voltage required and a voltage supplied are different. They are often used when a high voltage AC or DC power supply is provided, but a relatively lower voltage is needed. For example, a laptop battery might provide between 7 and 10 volts, while the circuitry within the laptop only needs a fraction of a volt. The voltage converter system acts to step down the voltage to the usable level.
A voltage conversion system generally includes a voltage converter (also called a plant) and a controller. In many voltage conversion systems, however, the controller is designed before it is known what kind of plant will be used. In some cases a given controller might be used for different plants throughout its life. For example, a consumer or a manufacturer might purchase or produce the controller and the plant separately and match the two as needed.
In such a case, the controller is generally designed assuming certain parameter values for the plant (e.g., inductance and capacitance values for elements within the plant). These are often represented by the poles and zeroes of the plant, i.e., the points on a Z-transform function of the plant where the Z-transform becomes infinity or zero, respectively. The poles and zeroes of a plant (or an assumption of these values) can be used as an indicator of system performance and stability under given conditions.
However, this kind of design process can often result in under-designing of the system in terms of: (a) the phase margin available for the system, which corresponds to the stability of the system, (b) the gain margin available to the system, which also corresponds to the stability of the system, (c) the settling time of the system to load transients, and (d) an effective O/P impedance of the system as seen from a load side. Without knowing exact parameters, the controller must be designed to handle a worst-case scenario.
Furthermore, even a perfectly balanced voltage converter system can degrade. Components in the plant will age, causing their parameters to drift over time. Thus, even with perfect knowledge of system components, it is often necessary to under-design the system to account for the aging of components in the plant.
As a result of this under-designing, conventional voltage conversion systems are generally less efficient and more wasteful than they need to be under most operating circumstances.
It would therefore be desirable to provide a device and method for automatically identifying plant parameters and automatically tuning (i.e., auto-tuning) a voltage conversion system. More particularly, it would be desirable to provide a controller device and related method that estimates the poles and zeroes of a plant.